Detection of submerged objects



June 11, 1946. J. H. HAMMOND, JR

DETECTION OF SUBMERGED OBJECTS Filed May 4, 1942 2 Sheets-Sheet 1 INVENTOR ZA-GL9Z9 June 1946- J. H. HAMMOND, JR

DETECTION OF SUBMERGED OBJECTS Filed May 4, 1942 2 Sheets-Sheet 2 Patented June 11, 1946 DETECTION OF SUBMEBGED OBJECTS John Hays Hammond, Jr., Gloucester, Mass, assignor to Radio Corporation of America, a corporation of Delaware Application May 4, 1942, Serial No. 441,713

3 Claims. 1

This invention relates to systems for the detection of submerged objects and more particularly to means for detecting changes in water penetrating rays caused by the presence of a submarine. p

More specifically the invention comprises means for projecting rays a considerable depth below the surface of the water and means for registering changes in intensity of such rays caused by the shadow of or by the reflection from a submerged object. Therays may comprise visible or invisible radiations'and may be produced by sources located below the surface, either stationary for protecting a harbor or towed behind a vessel for patrol purposes. The rays -may be received by receivers located at remote points or at different depths from the sources of radiationsand disposed to be influenced by the shadow of the object, or they may be received after reflection, either from the surface of the water or from the object, to be detected, on receivers located adjacent the sources. The receiving means. may operate as an indicating device for indicating the position of the submerged object The invention also consists in certain new and original features of construction and combinations of parts hereinafter set forth and claimed.

Although the novel features which are believed to becharacteristic of this invention will be particularly pointed out in the claims appended hereto, the invention itself, as to its objects and advantages, the mode of its operation and the mannet of its organization, may be better understood by referring to the following description taken in connection with the accompanying drawings forming a part hereof, in which Figure 1- is a schematic view of the radiations producing and receiving means, together with means for-towing same;

Figure 2 illustrates diagrammatically the receiving apparatus together with a position'indicator: a

Figure 3 illustrates diagrammatically a modifled form of receiving apparatus and indicator:

invisible radiations;

Figure 5 shows an apparatus for producing and receiving invisible radiations;

Figure 6 illustrates diagrammatically a light producing and receiving means which may be permanently located at the bottom of a harbor or channel; and Fi ure "7 illustrates diagrammatically a modifled form of light receiving apparatus.

Like reference characters denote like parts in the several figures of the drawings.

In the following descriptionand in the claims, parts will be identifiedby specific names for convenience, but they are intended to be as generic in their application to similar parts as the art will permit.

Referring to the accompanying drawings and more particularly to Figure 1, a towing means is shown, such, for example, as a vessel H to which is attached a cable I2. Secured to the cable l2 are a small paravane l3 and a large paravane which are adapted to be towed to two different depths, which, for example may be ten and one hundred feet respectively.

Fastened to the smaller paravane I3 is a cable It to which are attached at intervals-a plurality of radiation receiving bodies ll, known as flsh.

These may be similar in construction to the fish shown in U. S. Patent 1,625,245 to H. G. Dorsey. Fastened to the-larger paravane I5 is a cable It to which are attached a plurality of radiation emitting bodies l9, also known as fish. Each of the radiation-producing fish I9 is provided with a source of radiations mounted in the body of the fish and directed upward so as to produce a cone Electrical energy for producing these radiations is generated on the vessel I I and passes thru conductors provided in the cables l2 and IS. The radiations may comprise light rays; visible or invisible, compressional waves, electromagnetic radiations, or other radiations which are capable of transmission through the water.

The radiation receiving fish I! are shown in more detail in Figure 2 as applied to receivers for light rays, and comprise, in each case, a shell 2! which is provided with a transparent section 22 above which is mounted a cone shapedrefiector 23. At the apex of the reflector 23 is located a photo electric cell 25 which is connected in circuit with a battery 28 and a relay 21. A plurality of conductors, 28, 29, 30, etc. are provided in the cables I: and I6 and are connected to the Figure 4 shows an apparatus for producing drops of an annunciator 3|, the conductor 28 being connected to a battery 29a which supplies energy for the operation of the system. The conductor 28 is also connected to the armatures of all the relays 21 in the fish 11. Each of the conductors 29, 30, etc. is individually connected to the back contact of each of the relays 21.

Th'e annunciator 3| is located in any convenient position on the vessel H, 'such as in the pilot house.

In; the operation of the form of the invention 3 I showninF'igures1and2,thefish l'l'and llare towed by the vessel II and are maintained at predetermined depths in a well known manner by the action oi the paravanes I3 and II.

Each of the fish It produces a cone of radiations 2| which is projected upwards thru the water. The rays from each fish ll impinge on the photo-cell 25 of the corresponding fish I1 which energize the relay 21, thus opening the circuit to the corresponding drop in the annunciator ii. The annu'nciatorll is then reset in the usual manner. If any oi the fish I1 is not receiving radiations or if any 01 the photo-cells on their circuits is not functioning properly, the corresponding drop will remain down, indicating the location or the trouble.

The apparatus is towed thru the water by the vessel II. If a submarine should attempt to pass between any cooperating pair of fish l1 and It, a shadow will be cast on the corresponding fish [1, thus decreasing its illumination of the photo-cell 25. This will cause de-energization of the associated relay 21, which will cause the back contact of this relay to be closed, thus energizing the corresponding drop in the annunciator 3|, which will indicate, as by the numeral 2, the location of the submarine.

In this way, it is possible to detect the presence of a submarine at night. The illumination from the fish. It may be seen by aircraft flying above, so that it would also be possible for an observer in the aircraft to see a submarine passing thru the zone of illumination. 1! so desired, it is possible for the light from the fish It to be directed downward so as to illuminate the sea bottom, when it,is not too deep, and thus reveal the presence of a submarine resting on the bottom. This would be especially useful when the bottom is .sandy, as the dark hull of a submarine would be conspicuous against the light background of the sand. v

Figure 3 In the modified form of the invention depicted in Figure 3, the photocell 25 controls the operation of the relay 21 the back contact of which is in circuit-with'a battery as and an electromagnet 34. The armature 3B of the electromasnet It is pivoted at 38 and engages the tooth of a ratchet 31 against which. it is held by the action of a spring II. The ratchet 31 is secured to the end of a shaft 39 which is driven by a clockwork mechanism 40 or other suitable drive. i

The shaft 30 is provided with a section I of conducting material which is insulated from the The two brushes ll and ll are connected to two conductors 41 and M which. are housed in the towing cable Iland which run to 'all the fish l1 and to a bell 0 and battery II which may be located in the pilot house of the vessel II.

In the operation of the modified form or the invention shown in .Figure 3, when the photo-cell II is illuminated by the light from the fish II, it

will energize therelay 21 which will open the circuit to the electromagnet 84. This will allow the armature ii to engage the ratchet 31, thus holding the commutator 42 stationary so that thebrushllwillbeontheinsulationand circuit tothe bell ll open.

It a submarine should pass between a cooperdirection to release the ratchet 31, which will start turning slowly in a counter-clockwise direction under the action oi. the clockwork mechanism It. At the same time the commutator, will start to turn slowly. As the segments 48 engage the brush 4!, the circuit to the bell II will be completed causing it to ring.

As the segments 43 are arranged in groups corresponding to the location of the respective fish II, the bell will give a series of signals corresponding to the fish l1 which isover the submarine. For example, if the submarine is under the second fish l1, a, series of two rings will be produced, thus advising the captain of the vessel II that a submarine is located beneath the second fish.

Afterthe submarine has passed from beneath the fish l1, the photocell 28 will be again illuminated, which will energize the relay 21 and deenergize the electromagnet 84. The armature It will then drop onto the ratchet iTwhich will be stopped when the tooth oi this ratchet comes around into engagement with the armature ll.

The mechanism will then be in its inoperative position and the bell will stop ringing.

I Figure 4 In the modified form of the invention shown in Figure 4,the fish It is provided with a source of invisible radiation 55 which may be a vapor thru sea water is greatest in the range from about x3l00-M000 (article on "Penetration oi ultra violet light thru water, by E. O. Hulburt, Journal oi the Optical Society oi America, vol. 17, No. 1, July 1928).

The lamp I! is connected to the output side of a'transformer N the input side of which is connected to the power supply lines 51 and II which are contained in the cable It and which are supplied with suitable energy from the vessel H. The lamp Il may be mounted in a suitable re'fiector It. made of aluminum or other material having good-reflecting pr perties for ultra violet light.

The lamp 5| may be covered by a sheet of material I which is transparent to ultra violet light,

such, for example, as quartzor some suitable Plastic.

When this type or ultra violet 11am producing fish it is employed, the photo-electric cell II in the light receiving fish I1 should be oi a type which is especially suitable for receiving ultra violet light of the type emitted by the lamp ll,

such, for example, as the sodium, potassium or caesium photo-electric cells, which have their greatest sensitivity in the x3,000-M,000 region of the ultra violet spectrum.

The operation of the device shown in Figure 4 is similar to that described in connection with Figures 1 and 2 except that in this instance the light employed is in the invisible region oi the spectrum, so that it cannot be observed by the enemy and is thus not so apt to be avoided by them.

similar to that already described, to the contacts of the relays 21 and to the transformers 68.

In theoperation of the modifled'form of the invention shown in Figure 5, the relay 2'! is adlusted so that under normal conditions with only the light reflected and scattered by the sea water 1 on the photo electric cell 25, the contacts will be open. If a submarine or other vessel passes above the flsh I 9, a. certain amount of ultra violet light from the lamp 55 will be reflected from the vessel and will be received by the photo-electric cell 25, thus energizing this cell and causing the-operation of the relay 21 which, in turn, will operate the indicating device on the vessel II. In this way, only one set of fish will be necessary, thus simplifying the tow- 25 ing problem. If found desirable, a source of visiblelight could replace the lamp 55 and a photo-electric cell 25 sensitive to visible light could be employed.

Figures 6 and 7 In Figures 6 and 7 is shown a stationary system for detecting the presence of a submarine or other vessel. In this form of the invention a plurality of sources of illumination 55 are located on the bottom of a harbor or a channel and are connected by a. power cable 66 to a suitable source of energy located in a building 51. The sources of illumination 65 may produce ultra violet or visible light as desired. Located adjacent to the sources of illumination 85 are a plurality of light receivers 88 in which are mounted photo-electric cells 65 (Figure '7) and reflectors I0. The photoelectric cells 89 are connected thru batteries II tothe windings of balanced relays 12. The armatures a cable I1 and are connected to an annunciator 60 (not shown) located in the building 51 and which may be similar in construction to the annunciator 3i depicted in Figure 2. V

In the operation or the modified form of the invention shown in Elm s and mm relay 12 1 is adjusted so that, under normal conditions, the

armature will be in a central position and the contacts ,open. If a submarine or other vessel should pass above one of the light receivers 68,

5 a certain amount oflight will'be reflected to the 1 photo-electric cell 69 to increase the energization of the relay I2, which will close the upper contact and operate the annunciator in the building 61.

A submarine might passinsuch a way that the normal amount of light received by the photo'- electric cell 69 will be decreased, which will decrease the energization of the relay 12, thus closing the lower contact and causing the annunciator in the building 61 to operate. Although only a few of the various forms in which this invention may be embodied have been shown herein, it is tobe understood that the invention is not limited thereto but may be embodied in various forms within the scope of the appended claims.

' Whatisclaimedis:

1. A system for detecting the presence of a submerged object comprising a plurality ofysubmerged sources of water penetrating rays spaced from each other in a horizontal direction, a plurality. oi submerged receivers correspondingly spaced from each other in a horizontal direction and positioned to receive said rays after passage through the water, means for maintaining said sources and said receivers in superposed and vertically spaced, cooperative relation to each other whereby said object may be received therebetween at an intermediate elevation, said receivers being responsive to variations in intensity of the received waves, andmechanism actuated by said respective receivers in response to variations in intensity of the received waves produced by the presence of said object inthe path of said rays for indicating the actuating receiver.

'2. A system according to claim 1 in which towing means is provided to tow said sources and said receivers through the water in the area to be patrolled.

3. A system according to claim 1 in which towing means is provided to tow said sources and said receivers through the water in the area tohe patrolled, said towing means including a pair of cables to one of which said sources are connected and to the other of which said receivers I are connected, and a, paravane on each of said cables vso located thereon as to maintain each of said cables at a diilerent elevation in the water while being towed.

JOHN Ears HAMMOND, Ja. 

